本文实例讲述了mysql存储过程之返回多个值的方法。分享给大家供大家参考，具体如下：
mysql存储函数只返回一个值。要开发返回多个值的存储过程，需要使用带有INOUT或OUT参数的存储过程。咱们先来看一个orders表它的结构：
mysql> desc orders; +----------------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +----------------+-------------+------+-----+---------+-------+ | orderNumber | int(11) | NO | PRI | NULL | | | orderDate | date | NO | | NULL | | | requiredDate | date | NO | | NULL | | | shippedDate | date | YES | | NULL | | | status | varchar(15) | NO | | NULL | | | comments | text | YES | | NULL | | | customerNumber | int(11) | NO | MUL | NULL | | +----------------+-------------+------+-----+---------+-------+ 7 rows in set
然后嘞，咱们来看一个存储过程，它接受客户编号，并返回发货(shipped)，取消(canceled)，解决(resolved)和争议(disputed)的订单总数：
DELIMITER $$
CREATE PROCEDURE get_order_by_cust(
IN cust_no INT,
OUT shipped INT,
OUT canceled INT,
OUT resolved INT,
OUT disputed INT)
BEGIN
-- shipped
SELECT
count(*) INTO shipped
FROM
orders
WHERE
customerNumber = cust_no
AND status = 'Shipped';
-- canceled
SELECT
count(*) INTO canceled
FROM
orders
WHERE
customerNumber = cust_no
AND status = 'Canceled';
-- resolved
SELECT
count(*) INTO resolved
FROM
orders
WHERE
customerNumber = cust_no
AND status = 'Resolved';
-- disputed
SELECT
count(*) INTO disputed
FROM
orders
WHERE
customerNumber = cust_no
AND status = 'Disputed';
END
其实，除IN参数之外，存储过程还需要4个额外的OUT参数：shipped, canceled, resolved 和 disputed。 在存储过程中，使用带有count函数的select语句根据订单状态获取相应的订单总数，并将其分配给相应的参数。按着上面的sql，我们如果要使用get_order_by_cust存储过程，可以传递客户编号和四个用户定义的变量来获取输出值。执行存储过程后，我们再使用SELECT语句输出变量值：
+----------+-----------+-----------+-----------+ | @shipped | @canceled | @resolved | @disputed | +----------+-----------+-----------+-----------+ | 22 | 0 | 1 | 1 | +----------+-----------+-----------+-----------+ 1 row in set
结合实际应用，我们再来看下从PHP程序中调用返回多个值的存储过程：
<?php
/**
* Call stored procedure that return multiple values
* @param $customerNumber
*/
function call_sp($customerNumber)
{
try {
$pdo = new PDO("mysql:host=localhost;dbname=yiibaidb", 'root', '123456');
// execute the stored procedure
$sql = 'CALL get_order_by_cust(:no,@shipped,@canceled,@resolved,@disputed)';
$stmt = $pdo->prepare($sql);
$stmt->bindParam(':no', $customerNumber, PDO::PARAM_INT);
$stmt->execute();
$stmt->closeCursor();
// execute the second query to get values from OUT parameter
$r = $pdo->query("SELECT @shipped,@canceled,@resolved,@disputed")
->fetch(PDO::FETCH_ASSOC);
if ($r) {
printf('Shipped: %d, Canceled: %d, Resolved: %d, Disputed: %d',
$r['@shipped'],
$r['@canceled'],
$r['@resolved'],
$r['@disputed']);
}
} catch (PDOException $pe) {
die("Error occurred:" . $pe->getMessage());
}
}
call_sp(141);
上述代码中，在@符号之前的用户定义的变量与数据库连接相关联，因此它们可用于在调用之间进行访问。
好啦，本次分享就到这里了。
更多关于MySQL相关内容感兴趣的读者可查看本站专题：《MySQL存储过程技巧大全》、《MySQL常用函数大汇总》、《MySQL日志操作技巧大全》、《MySQL事务操作技巧汇总》及《MySQL数据库锁相关技巧汇总》
希望本文所述对大家MySQL数据库计有所帮助。
